Originally Posted by dchalfont
Thanks for all the tips. I am way happier with my sb-4000 now and really looking forward to getting my second one. I was a bit depressed about selling my 2 subs to buy this ine and then running into trouble.
I set the sub to -6dB in the receiver and was able to tirn the sub from -25 to -12 and still not run into the kind of distortion if that's what you could call it that I had before.
At -22 when I ran the test last it recommend that I set the receiver to -4. But at -12 it is saying to set it to -10 on the receiver which is as low as it goes and so I ran the test again at -15 gain on the sub and it said to set it to -7.5 on the receiver.
I really feel that the volume on the sub is the same at -12 with -6 on the receiver as it was with -25 with 0dB on the receiver but maybe without the distortion it just sounds different.
I think the fact that according to those tests -12db is 0.5db higher than when it would start to recommend increasing the volume on the sub means I am at the perfect point now.
Will have to test more at some point but kids are asleep now.
Will listen to some music with a beat but quietly because before at -25 to beat the distorted LFE in that scene it made muaic weak. I hope now I can have one setting for everything.
Is there any way to do the maths on the end volume. I know it's not just like plus and minus equals with volume right?
I want to know what the volume of the sub is compared with before because it's hard to tell with the distortion gone. Because in theory it is 7dB louder than before but I fell like it might be a few dB quieter, I just didn't want to push my luck.
0 trim -25 sub is -25 but it the receiver-6 and the sub is -12 I don't think it's as simple as -18 total.
I can't believe they sell top of the line receivers that clip the $#!+ out of the signal at 0db sub level/trim.
The overriding theme here needs to be the subwoofer calibration level, relative to that of the speaker channels.
Discussing the subwoofer volume (gain) setting, the AVR sub channel level, or even the sub volume and
the sub channel level - really doesn't tell us the actual calibration level of the subwoofer., relative to that of the speaker channels.
The level matching of all channels (including the subwoofer) is accomplished during auto-set-up. And even then - if the subwoofer gain is set too high - sometimes the AV processor won't be able to level match the subwoofer without running out of trim. Some AV processors give you a warning about this - most do not. The only potential clue is the AVR sub channel level is bottomed out at the minimum value after set-up is run.
If you have a real SPL meter with C/Slow (like a Galaxy CM-130) - it can be used as a sanity check for level matching all channels, including the subwoofer. The C-weighted filter will typically read 2-3 dB LOW on the rumble tone - so account for that when level matching.
Regardless, if the subwoofer is level matched to the speaker channels (via auto-set-up or an SPL meter), the chances of it overloading on any particular scene (like the RP1 referenced above) is greatly reduced.
It's very possible (likely even) that a 0 dB subwoofer volume and a 0 dB AVR sub channel level with an SB-4000 will result in the subwoofer being 10-20 dB too hot - and is just ends-up being a compressed droning mess with no dynamic range. The quiet bass is way too loud - and the loudest bass won't get any louder than the DSP limiter/compressor allows.
The best advice I can offer here is to re-run auto-set-up, making sure the post-calibration AVR subwoofer channel level isn't bottomed out at the minimum value. If that occurs - lower the subwoofer volume/gain and re-run set-up until you get something other than the minimum value. At that point, the combination of the subwoofer volume/gain and
the post-calibration subwoofer channel level accurately defines the true level match for the subwoofer channel.
Any upward deviations from that baseline combination is - by definition - running the subwoofer channel 'hot'. How hot is a matter of subjective preference which seems chronically up for debate. But suffice it to say - adding gain over the baseline calibration level chews up dynamic headroom which would otherwise be available for the subwoofer to play demanding peaks without running into compression.
To the extent personal preference for 'hotness' and the overall system playback level is inconsistent with the maximum uncompressed dynamic output limits of the subwoofer - the typical recommendation is to add another subwoofer or upgrade to a more powerful subwoofer - with the end goal being uncompressed (or minimally compressed) playback of the subwoofer channel.